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        <h1>Node.js v6.9.1 Documentation</h1>
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        <h2>Table of Contents</h2>
        <ul>
<li><a href="#readline_readline">Readline</a><ul>
<li><a href="#readline_class_interface">Class: Interface</a><ul>
<li><a href="#readline_event_close">Event: &#39;close&#39;</a></li>
<li><a href="#readline_event_line">Event: &#39;line&#39;</a></li>
<li><a href="#readline_event_pause">Event: &#39;pause&#39;</a></li>
<li><a href="#readline_event_resume">Event: &#39;resume&#39;</a></li>
<li><a href="#readline_event_sigcont">Event: &#39;SIGCONT&#39;</a></li>
<li><a href="#readline_event_sigint">Event: &#39;SIGINT&#39;</a></li>
<li><a href="#readline_event_sigtstp">Event: &#39;SIGTSTP&#39;</a></li>
<li><a href="#readline_rl_close">rl.close()</a></li>
<li><a href="#readline_rl_pause">rl.pause()</a></li>
<li><a href="#readline_rl_prompt_preservecursor">rl.prompt([preserveCursor])</a></li>
<li><a href="#readline_rl_question_query_callback">rl.question(query, callback)</a></li>
<li><a href="#readline_rl_resume">rl.resume()</a></li>
<li><a href="#readline_rl_setprompt_prompt">rl.setPrompt(prompt)</a></li>
<li><a href="#readline_rl_write_data_key">rl.write(data[, key])</a></li>
</ul>
</li>
<li><a href="#readline_readline_clearline_stream_dir">readline.clearLine(stream, dir)</a></li>
<li><a href="#readline_readline_clearscreendown_stream">readline.clearScreenDown(stream)</a></li>
<li><a href="#readline_readline_createinterface_options">readline.createInterface(options)</a><ul>
<li><a href="#readline_use_of_the_completer_function">Use of the <code>completer</code> Function</a></li>
</ul>
</li>
<li><a href="#readline_readline_cursorto_stream_x_y">readline.cursorTo(stream, x, y)</a></li>
<li><a href="#readline_readline_emitkeypressevents_stream_interface">readline.emitKeypressEvents(stream[, interface])</a></li>
<li><a href="#readline_readline_movecursor_stream_dx_dy">readline.moveCursor(stream, dx, dy)</a></li>
<li><a href="#readline_example_tiny_cli">Example: Tiny CLI</a></li>
<li><a href="#readline_example_read_file_stream_line_by_line">Example: Read File Stream Line-by-Line</a></li>
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      <div id="apicontent">
        <h1>Readline<span><a class="mark" href="#readline_readline" id="readline_readline">#</a></span></h1>
<pre class="api_stability api_stability_2">Stability: 2 - Stable</pre><p>The <code>readline</code> module provides an interface for reading data from a <a href="stream.html">Readable</a>
stream (such as <a href="process.html#process_process_stdin"><code>process.stdin</code></a>) one line at a time. It can be accessed using:</p>
<pre><code class="lang-js">const readline = require(&#39;readline&#39;);
</code></pre>
<p>The following simple example illustrates the basic use of the <code>readline</code> module.</p>
<pre><code class="lang-js">const readline = require(&#39;readline&#39;);

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

rl.question(&#39;What do you think of Node.js? &#39;, (answer) =&gt; {
  // TODO: Log the answer in a database
  console.log(&#39;Thank you for your valuable feedback:&#39;, answer);

  rl.close();
});
</code></pre>
<p><em>Note</em> Once this code is invoked, the Node.js application will not
terminate until the <code>readline.Interface</code> is closed because the interface
waits for data to be received on the <code>input</code> stream.</p>
<h2>Class: Interface<span><a class="mark" href="#readline_class_interface" id="readline_class_interface">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.1.104</span>
</div><p>Instances of the <code>readline.Interface</code> class are constructed using the
<code>readline.createInterface()</code> method. Every instance is associated with a
single <code>input</code> <a href="stream.html">Readable</a> stream and a single <code>output</code> <a href="stream.html">Writable</a> stream.
The <code>output</code> stream is used to print prompts for user input that arrives on,
and is read from, the <code>input</code> stream.</p>
<h3>Event: &#39;close&#39;<span><a class="mark" href="#readline_event_close" id="readline_event_close">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.98</span>
</div><p>The <code>&#39;close&#39;</code> event is emitted when one of the following occur:</p>
<ul>
<li>The <code>rl.close()</code> method is called and the <code>readline.Interface</code> instance has
relinquished control over the <code>input</code> and <code>output</code> streams;</li>
<li>The <code>input</code> stream receives its <code>&#39;end&#39;</code> event;</li>
<li>The <code>input</code> stream receives <code>&lt;ctrl&gt;-D</code> to signal end-of-transmission (EOT);</li>
<li>The <code>input</code> stream receives <code>&lt;ctrl&gt;-C</code> to signal <code>SIGINT</code> and there is no
<code>SIGINT</code> event listener registered on the <code>readline.Interface</code> instance.</li>
</ul>
<p>The listener function is called without passing any arguments.</p>
<p>The <code>readline.Interface</code> instance should be considered to be &quot;finished&quot; once
the <code>&#39;close&#39;</code> event is emitted.</p>
<h3>Event: &#39;line&#39;<span><a class="mark" href="#readline_event_line" id="readline_event_line">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.98</span>
</div><p>The <code>&#39;line&#39;</code> event is emitted whenever the <code>input</code> stream receives an
end-of-line input (<code>\n</code>, <code>\r</code>, or <code>\r\n</code>). This usually occurs when the user
presses the <code>&lt;Enter&gt;</code>, or <code>&lt;Return&gt;</code> keys.</p>
<p>The listener function is called with a string containing the single line of
received input.</p>
<p>For example:</p>
<pre><code class="lang-js">rl.on(&#39;line&#39;, (input) =&gt; {
  console.log(`Received: ${input}`);
});
</code></pre>
<h3>Event: &#39;pause&#39;<span><a class="mark" href="#readline_event_pause" id="readline_event_pause">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.7.5</span>
</div><p>The <code>&#39;pause&#39;</code> event is emitted when one of the following occur:</p>
<ul>
<li>The <code>input</code> stream is paused.</li>
<li>The <code>input</code> stream is not paused and receives the <code>SIGCONT</code> event. (See
events <a href="readline.html#readline_event_sigtstp"><code>SIGTSTP</code></a> and <a href="readline.html#readline_event_sigcont"><code>SIGCONT</code></a>)</li>
</ul>
<p>The listener function is called without passing any arguments.</p>
<p>For example:</p>
<pre><code class="lang-js">rl.on(&#39;pause&#39;, () =&gt; {
  console.log(&#39;Readline paused.&#39;);
});
</code></pre>
<h3>Event: &#39;resume&#39;<span><a class="mark" href="#readline_event_resume" id="readline_event_resume">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.7.5</span>
</div><p>The <code>&#39;resume&#39;</code> event is emitted whenever the <code>input</code> stream is resumed.</p>
<p>The listener function is called without passing any arguments.</p>
<pre><code class="lang-js">rl.on(&#39;resume&#39;, () =&gt; {
  console.log(&#39;Readline resumed.&#39;);
});
</code></pre>
<h3>Event: &#39;SIGCONT&#39;<span><a class="mark" href="#readline_event_sigcont" id="readline_event_sigcont">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.7.5</span>
</div><p>The <code>&#39;SIGCONT&#39;</code> event is emitted when a Node.js process previously moved into
the background using <code>&lt;ctrl&gt;-Z</code> (i.e. <code>SIGTSTP</code>) is then brought back to the
foreground using <code>fg(1)</code>.</p>
<p>If the <code>input</code> stream was paused <em>before</em> the <code>SIGTSTP</code> request, this event will
not be emitted.</p>
<p>The listener function is invoked without passing any arguments.</p>
<p>For example:</p>
<pre><code class="lang-js">rl.on(&#39;SIGCONT&#39;, () =&gt; {
  // `prompt` will automatically resume the stream
  rl.prompt();
});
</code></pre>
<p><em>Note</em>: The <code>&#39;SIGCONT&#39;</code> event is <em>not</em> supported on Windows.</p>
<h3>Event: &#39;SIGINT&#39;<span><a class="mark" href="#readline_event_sigint" id="readline_event_sigint">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.3.0</span>
</div><p>The <code>&#39;SIGINT&#39;</code> event is emitted whenever the <code>input</code> stream receives a
<code>&lt;ctrl&gt;-C</code> input, known typically as <code>SIGINT</code>. If there are no <code>&#39;SIGINT&#39;</code> event
listeners registered when the <code>input</code> stream receives a <code>SIGINT</code>, the <code>&#39;pause&#39;</code>
event will be emitted.</p>
<p>The listener function is invoked without passing any arguments.</p>
<p>For example:</p>
<pre><code class="lang-js">rl.on(&#39;SIGINT&#39;, () =&gt; {
  rl.question(&#39;Are you sure you want to exit?&#39;, (answer) =&gt; {
    if (answer.match(/^y(es)?$/i)) rl.pause();
  });
});
</code></pre>
<h3>Event: &#39;SIGTSTP&#39;<span><a class="mark" href="#readline_event_sigtstp" id="readline_event_sigtstp">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.7.5</span>
</div><p>The <code>&#39;SIGTSTP&#39;</code> event is emitted when the <code>input</code> stream receives a <code>&lt;ctrl&gt;-Z</code>
input, typically known as <code>SIGTSTP</code>. If there are no <code>SIGTSTP</code> event listeners
registered when the <code>input</code> stream receives a <code>SIGTSTP</code>, the Node.js process
will be sent to the background.</p>
<p>When the program is resumed using <code>fg(1)</code>, the <code>&#39;pause&#39;</code> and <code>SIGCONT</code> events
will be emitted. These can be used to resume the <code>input</code> stream.</p>
<p>The <code>&#39;pause&#39;</code> and <code>&#39;SIGCONT&#39;</code> events will not be emitted if the <code>input</code> was
paused before the process was sent to the background.</p>
<p>The listener function is invoked without passing any arguments.</p>
<p>For example:</p>
<pre><code class="lang-js">rl.on(&#39;SIGTSTP&#39;, () =&gt; {
  // This will override SIGTSTP and prevent the program from going to the
  // background.
  console.log(&#39;Caught SIGTSTP.&#39;);
});
</code></pre>
<p><em>Note</em>: The <code>&#39;SIGTSTP&#39;</code> event is <em>not</em> supported on Windows.</p>
<h3>rl.close()<span><a class="mark" href="#readline_rl_close" id="readline_rl_close">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.98</span>
</div><p>The <code>rl.close()</code> method closes the <code>readline.Interface</code> instance and
relinquishes control over the <code>input</code> and <code>output</code> streams. When called,
the <code>&#39;close&#39;</code> event will be emitted.</p>
<h3>rl.pause()<span><a class="mark" href="#readline_rl_pause" id="readline_rl_pause">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.3.4</span>
</div><p>The <code>rl.pause()</code> method pauses the <code>input</code> stream, allowing it to be resumed
later if necessary.</p>
<p>Calling <code>rl.pause()</code> does not immediately pause other events (including
<code>&#39;line&#39;</code>) from being emitted by the <code>readline.Interface</code> instance.</p>
<h3>rl.prompt([preserveCursor])<span><a class="mark" href="#readline_rl_prompt_preservecursor" id="readline_rl_prompt_preservecursor">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.98</span>
</div><ul>
<li><code>preserveCursor</code> <span class="type">&lt;boolean&gt;</span> If <code>true</code>, prevents the cursor placement from
being reset to <code>0</code>.</li>
</ul>
<p>The <code>rl.prompt()</code> method writes the <code>readline.Interface</code> instances configured
<code>prompt</code> to a new line in <code>output</code> in order to provide a user with a new
location at which to provide input.</p>
<p>When called, <code>rl.prompt()</code> will resume the <code>input</code> stream if it has been
paused.</p>
<p>If the <code>readline.Interface</code> was created with <code>output</code> set to <code>null</code> or
<code>undefined</code> the prompt is not written.</p>
<h3>rl.question(query, callback)<span><a class="mark" href="#readline_rl_question_query_callback" id="readline_rl_question_query_callback">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.3.3</span>
</div><ul>
<li><code>query</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&lt;String&gt;</a> A statement or query to write to <code>output</code>, prepended to the
prompt.</li>
<li><code>callback</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&lt;Function&gt;</a> A callback function that is invoked with the user&#39;s
input in response to the <code>query</code>.</li>
</ul>
<p>The <code>rl.question()</code> method displays the <code>query</code> by writing it to the <code>output</code>,
waits for user input to be provided on <code>input</code>, then invokes the <code>callback</code>
function passing the provided input as the first argument.</p>
<p>When called, <code>rl.question()</code> will resume the <code>input</code> stream if it has been
paused.</p>
<p>If the <code>readline.Interface</code> was created with <code>output</code> set to <code>null</code> or
<code>undefined</code> the <code>query</code> is not written.</p>
<p>Example usage:</p>
<pre><code class="lang-js">rl.question(&#39;What is your favorite food?&#39;, (answer) =&gt; {
  console.log(`Oh, so your favorite food is ${answer}`);
});
</code></pre>
<p><em>Note</em>: The <code>callback</code> function passed to <code>rl.question()</code> does not follow the
typical pattern of accepting an <code>Error</code> object or <code>null</code> as the first argument.
The <code>callback</code> is called with the provided answer as the only argument.</p>
<h3>rl.resume()<span><a class="mark" href="#readline_rl_resume" id="readline_rl_resume">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.3.4</span>
</div><p>The <code>rl.resume()</code> method resumes the <code>input</code> stream if it has been paused.</p>
<h3>rl.setPrompt(prompt)<span><a class="mark" href="#readline_rl_setprompt_prompt" id="readline_rl_setprompt_prompt">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.98</span>
</div><ul>
<li><code>prompt</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&lt;String&gt;</a></li>
</ul>
<p>The <code>rl.setPrompt()</code> method sets the prompt that will be written to <code>output</code>
whenever <code>rl.prompt()</code> is called.</p>
<h3>rl.write(data[, key])<span><a class="mark" href="#readline_rl_write_data_key" id="readline_rl_write_data_key">#</a></span></h3>
<div class="api_metadata">
<span>Added in: v0.1.98</span>
</div><ul>
<li><code>data</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&lt;String&gt;</a></li>
<li><code>key</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&lt;Object&gt;</a><ul>
<li><code>ctrl</code> <span class="type">&lt;boolean&gt;</span> <code>true</code> to indicate the <code>&lt;ctrl&gt;</code> key.</li>
<li><code>meta</code> <span class="type">&lt;boolean&gt;</span> <code>true</code> to indicate the <code>&lt;Meta&gt;</code> key.</li>
<li><code>shift</code> <span class="type">&lt;boolean&gt;</span> <code>true</code> to indicate the <code>&lt;Shift&gt;</code> key.</li>
<li><code>name</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type">&lt;String&gt;</a> The name of the a key.</li>
</ul>
</li>
</ul>
<p>The <code>rl.write()</code> method will write either <code>data</code> or a key sequence  identified
by <code>key</code> to the <code>output</code>. The <code>key</code> argument is supported only if <code>output</code> is
a <a href="tty.html">TTY</a> text terminal.</p>
<p>If <code>key</code> is specified, <code>data</code> is ignored.</p>
<p>When called, <code>rl.write()</code> will resume the <code>input</code> stream if it has been
paused.</p>
<p>If the <code>readline.Interface</code> was created with <code>output</code> set to <code>null</code> or
<code>undefined</code> the <code>data</code> and <code>key</code> are not written.</p>
<p>For example:</p>
<pre><code class="lang-js">rl.write(&#39;Delete this!&#39;);
// Simulate Ctrl+u to delete the line written previously
rl.write(null, {ctrl: true, name: &#39;u&#39;});
</code></pre>
<p><em>Note</em>: The <code>rl.write()</code> method will write the data to the <code>readline</code>
Interface&#39;s <code>input</code> <em>as if it were provided by the user</em>.</p>
<h2>readline.clearLine(stream, dir)<span><a class="mark" href="#readline_readline_clearline_stream_dir" id="readline_readline_clearline_stream_dir">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.7.7</span>
</div><ul>
<li><code>stream</code> <span class="type">&lt;Writable&gt;</span></li>
<li><code>dir</code> <span class="type">&lt;number&gt;</span><ul>
<li><code>-1</code> - to the left from cursor</li>
<li><code>1</code> - to the right from cursor</li>
<li><code>0</code> - the entire line</li>
</ul>
</li>
</ul>
<p>The <code>readline.clearLine()</code> method clears current line of given <a href="tty.html">TTY</a> stream
in a specified direction identified by <code>dir</code>.</p>
<h2>readline.clearScreenDown(stream)<span><a class="mark" href="#readline_readline_clearscreendown_stream" id="readline_readline_clearscreendown_stream">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.7.7</span>
</div><ul>
<li><code>stream</code> <span class="type">&lt;Writable&gt;</span></li>
</ul>
<p>The <code>readline.clearScreenDown()</code> method clears the given <a href="tty.html">TTY</a> stream from
the current position of the cursor down.</p>
<h2>readline.createInterface(options)<span><a class="mark" href="#readline_readline_createinterface_options" id="readline_readline_createinterface_options">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.1.98</span>
</div><ul>
<li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type">&lt;Object&gt;</a><ul>
<li><code>input</code> <span class="type">&lt;Readable&gt;</span> The <a href="stream.html">Readable</a> stream to listen to. This option is
<em>required</em>.</li>
<li><code>output</code> <span class="type">&lt;Writable&gt;</span> The <a href="stream.html">Writable</a> stream to write readline data to.</li>
<li><code>completer</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function" class="type">&lt;Function&gt;</a> An optional function used for Tab autocompletion.</li>
<li><code>terminal</code> <span class="type">&lt;boolean&gt;</span> <code>true</code> if the <code>input</code> and <code>output</code> streams should be
treated like a TTY, and have ANSI/VT100 escape codes written to it.
Defaults to checking <code>isTTY</code> on the <code>output</code> stream upon instantiation.</li>
<li><code>historySize</code> <span class="type">&lt;number&gt;</span> maximum number of history lines retained. To disable
the history set this value to <code>0</code>. Defaults to <code>30</code>. This option makes sense
only if <code>terminal</code> is set to <code>true</code> by the user or by an internal <code>output</code>
check, otherwise the history caching mechanism is not initialized at all.</li>
<li><code>prompt</code> - the prompt string to use. Default: <code>&#39;&gt; &#39;</code></li>
<li><code>crlfDelay</code> <span class="type">&lt;number&gt;</span> If the delay between <code>\r</code> and <code>\n</code> exceeds
<code>crlfDelay</code> milliseconds, both <code>\r</code> and <code>\n</code> will be treated as separate
end-of-line input. Default to <code>100</code> milliseconds.
<code>crlfDelay</code> will be coerced to <code>[100, 2000]</code> range.</li>
</ul>
</li>
</ul>
<p>The <code>readline.createInterface()</code> method creates a new <code>readline.Interface</code>
instance.</p>
<p>For example:</p>
<pre><code class="lang-js">const readline = require(&#39;readline&#39;);
const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});
</code></pre>
<p>Once the <code>readline.Interface</code> instance is created, the most common case is to
listen for the <code>&#39;line&#39;</code> event:</p>
<pre><code class="lang-js">rl.on(&#39;line&#39;, (line) =&gt; {
  console.log(`Received: ${line}`);
});
</code></pre>
<p>If <code>terminal</code> is <code>true</code> for this instance then the <code>output</code> stream will get
the best compatibility if it defines an <code>output.columns</code> property and emits
a <code>&#39;resize&#39;</code> event on the <code>output</code> if or when the columns ever change
(<a href="process.html#process_process_stdout"><code>process.stdout</code></a> does this automatically when it is a TTY).</p>
<h3>Use of the <code>completer</code> Function<span><a class="mark" href="#readline_use_of_the_completer_function" id="readline_use_of_the_completer_function">#</a></span></h3>
<p>When called, the <code>completer</code> function is provided the current line entered by
the user, and is expected to return an Array with 2 entries:</p>
<ul>
<li>An Array with matching entries for the completion.</li>
<li>The substring that was used for the matching.</li>
</ul>
<p>For instance: <code>[[substr1, substr2, ...], originalsubstring]</code>.</p>
<pre><code class="lang-js">function completer(line) {
  var completions = &#39;.help .error .exit .quit .q&#39;.split(&#39; &#39;);
  var hits = completions.filter((c) =&gt; { return c.indexOf(line) == 0 });
  // show all completions if none found
  return [hits.length ? hits : completions, line];
}
</code></pre>
<p>The <code>completer</code> function can be called asynchronously if it accepts two
arguments:</p>
<pre><code class="lang-js">function completer(linePartial, callback) {
  callback(null, [[&#39;123&#39;], linePartial]);
}
</code></pre>
<h2>readline.cursorTo(stream, x, y)<span><a class="mark" href="#readline_readline_cursorto_stream_x_y" id="readline_readline_cursorto_stream_x_y">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.7.7</span>
</div><ul>
<li><code>stream</code> <span class="type">&lt;Writable&gt;</span></li>
<li><code>x</code> <span class="type">&lt;number&gt;</span></li>
<li><code>y</code> <span class="type">&lt;number&gt;</span></li>
</ul>
<p>The <code>readline.cursorTo()</code> method moves cursor to the specified position in a
given <a href="tty.html">TTY</a> <code>stream</code>.</p>
<h2>readline.emitKeypressEvents(stream[, interface])<span><a class="mark" href="#readline_readline_emitkeypressevents_stream_interface" id="readline_readline_emitkeypressevents_stream_interface">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.7.7</span>
</div><ul>
<li><code>stream</code> <span class="type">&lt;Readable&gt;</span></li>
<li><code>interface</code> <span class="type">&lt;readline.Interface&gt;</span></li>
</ul>
<p>The <code>readline.emitKeypressEvents()</code> method causes the given <a href="stream.html">Writable</a>
<code>stream</code> to begin emitting <code>&#39;keypress&#39;</code> events corresponding to received input.</p>
<p>Optionally, <code>interface</code> specifies a <code>readline.Interface</code> instance for which
autocompletion is disabled when copy-pasted input is detected.</p>
<p>If the <code>stream</code> is a <a href="tty.html">TTY</a>, then it must be in raw mode.</p>
<pre><code class="lang-js">readline.emitKeypressEvents(process.stdin);
if (process.stdin.isTTY)
  process.stdin.setRawMode(true);
</code></pre>
<h2>readline.moveCursor(stream, dx, dy)<span><a class="mark" href="#readline_readline_movecursor_stream_dx_dy" id="readline_readline_movecursor_stream_dx_dy">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.7.7</span>
</div><ul>
<li><code>stream</code> <span class="type">&lt;Writable&gt;</span></li>
<li><code>dx</code> <span class="type">&lt;number&gt;</span></li>
<li><code>dy</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type">&lt;Number&gt;</a></li>
</ul>
<p>The <code>readline.moveCursor()</code> method moves the cursor <em>relative</em> to its current
position in a given <a href="tty.html">TTY</a> <code>stream</code>.</p>
<h2>Example: Tiny CLI<span><a class="mark" href="#readline_example_tiny_cli" id="readline_example_tiny_cli">#</a></span></h2>
<p>The following example illustrates the use of <code>readline.Interface</code> class to
implement a small command-line interface:</p>
<pre><code class="lang-js">const readline = require(&#39;readline&#39;);
const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  prompt: &#39;OHAI&gt; &#39;
});

rl.prompt();

rl.on(&#39;line&#39;, (line) =&gt; {
  switch(line.trim()) {
    case &#39;hello&#39;:
      console.log(&#39;world!&#39;);
      break;
    default:
      console.log(`Say what? I might have heard &#39;${line.trim()}&#39;`);
      break;
  }
  rl.prompt();
}).on(&#39;close&#39;, () =&gt; {
  console.log(&#39;Have a great day!&#39;);
  process.exit(0);
});
</code></pre>
<h2>Example: Read File Stream Line-by-Line<span><a class="mark" href="#readline_example_read_file_stream_line_by_line" id="readline_example_read_file_stream_line_by_line">#</a></span></h2>
<p>A common use case for <code>readline</code> is to consume input from a filesystem
<a href="stream.html">Readable</a> stream one line at a time, as illustrated in the following
example:</p>
<pre><code class="lang-js">const readline = require(&#39;readline&#39;);
const fs = require(&#39;fs&#39;);

const rl = readline.createInterface({
  input: fs.createReadStream(&#39;sample.txt&#39;)
});

rl.on(&#39;line&#39;, (line) =&gt; {
  console.log(&#39;Line from file:&#39;, line);
});
</code></pre>

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